Felt and process of making same



Patented Feb. 4, 1936 PATENT OFFICE 2,029,310- FELT AND, PRdCESS OF MAKING SAME Pierre Drewsen, Sandusky, Ohio, assignor to The Barrett Company, a corporation of New Jersey No Drawing. Application February 4, 1926, Serial No. 86,098. Renewed January 2'1, 1934 33 Claims.

This invention relatw to the production of paper or felt. It relates particularly to processes of producing felt, suitable for saturation with tar, asphalt or other saturants or waterproofing materials,.which may be used, for example, for building, sheathing, roofing or other purposes.

Heretofore the manufacture of saturating felt has been accomplished by the utilization of one or more of the following materials: #1 rags,

which contain substantially a mixture of cotton and wool; #2 rags, which contain substantially cotton; #3 rags, which contain jute fiber in the form of waste bagging; #4 rags, which contain substantially oldcarpets, composed largely of j jute, with quantities of cotton andwool; #5 rags, which contain rag clippings of all grades with varying amounts of paper; and paper stock, composed largely of waste paper. These materials are partially disintegrated in rag cutters and,

g0 thereafter, while in suspension in water, are beaten in paper mill heaters, then jordanned if desired and finally formed into a continuous sheet of paper on Fourdrinier or cylinder paper mar chinesf a My invention contemplates the treatment of cereal and other annual crop fibers and other vegetable fibers in such a manner as to produce fibers'of three classes, to wit: (1) fibers in which strength is the predominating characteristic; 30 (2) fibers of high absorptive capacity; (3) filler fibers relatively low. in saturating capacity and strength. My invention further contemplates the blending of two or more of these three classes of fibers in such a manner, as is hereinafter more 3:, fully described, as to produce a sheet of felt having the requisite strength and absorptive capacity for the purpose for which it is intended to be used. a

All unsized and moderately well beaten fibers 40 which will run on a paper-making machine and form a sheet of paper have some strength and some. saturating capacity, it being usually the case, however, that as the comparative strength of a fiber. is increased as, for instance, 'by pro- 45 longed beating, the comparative saturating capacity thereof is diminished. The 'amountof saturant which felt paper will absorb,besides de-= pending upon the absorptive capacity of thesheet, depends upon the condition of saturationss' tured to absorb a relatively small-amount of setsuch as-time of immersion of the sheet, tempera-- .percentage of asphalt absorbed sometimes ex- 5 ceeding 200%. In general, therefore, where felts of all kinds, both slightly and highly absorbent,

are made it is desirable to have strength-giving fibers, good saturant carrying fibers and fibers to control saturating qualities. 0 Of these three classes of fibers, those to be used principally for imparting the element of strength to a sheet of saturating felt may be prepared as follows: Jutefthat is waste bagging otherwise called #3 rags, is cooked by the calcium pentasulphide process, substantially as described in U. S .Patent No. 996,225, to Viggo Drewsen granted June 27, 1911 is then washed until free fromspent cooking liquors and afterward defibered in a beating engine. The fiber thus produced has 'been found to be greatly difierent in character from the uncooked bagging or jute as known to the prior art. Polysulphides of certain other alkali or'alkali earth metals may be used instead of calcium pentasulphide with similar results. Good results have also been obtained in producing a strength fiber by cooking raw jute or jute bagging, at an elevated temperature of from 130 to 150 0., in a solution of sodium carbonate coni I taining about 10% by weight of sodium carbonate based on the weight of the raw fiber being cooked.

It may be desirable to use a 10% solution'of lime instead of the sodium carbonate solution.

Flax tow, made from American or Canadian fiax straw by the well known breaking process, by which the shive or interior woody portion is largely removed, has been found to also give a very useful strength fiber when treated in a manner similar to that above set forth.

It has alsobeen found that a strength fiber 40 may be produced from jute or fiax tow by treating same inthe ordinary type of beating engine V with water at 90 to 100 C., to which approxi- -mately 10% more or less of alkali, such ascaustic soda,.caustic lime; etc., based upon 'the dry weight of the fiber to be treated, has been added. The fiber, of course, should be thoroughly washed with water before it is used as a component in the felt.

It has also been found that unbleached sulphite ,or kraft' pulp may be used successfully as a strength fiber in my formula: for producing felt.

Of these three classes of fibers, those to be used principally for imparting high absorptive capacity to ."am of saturating felt Prepared as follows: Spruce or hemlock, chips or the above calcium pentasulphide process or by may be shavings may becooked by the sodium pentasulphide process, after which the fibers are disintegrated by treatment with edge runners or in the ordinary form of beating engine or Jordan engines Wood mayalso be treated at elevated temperatures of 90? to 100 C. in the ordinary type of bea e ine in a solution of causticsodaor similarly acting alkali, the amount of alkali in the solution being equal to more than of the drygweight of the wood substances, after which .th fibrous substance is washed and disintegratedin .a beating engine;

Absorptive treating wheat stra rye straw, oat straw, rice straw or barley straw or other cereal or annual .crop fiber in a digester with water at elevated temperatures, for instance, from 120' to 150 6., for a short period of time sufiicient only to thoroughly soak the fibrous material, which material isthen disintegrated in the ordinary types:

beating engine. This type of fiber may also be produced from the same raw terials by heating said fibers at lower tempfi-ztures. such for instance as 90-100 C. When beating such matel'lalsat about 50 C. it has been found more satisfactory to addjabout 10% sodium carbonate. When beating such materials at atmospheric temperature, sodium carbonate may "be replaced by caustic soda, altho such substitution tends to increase the rapidityof the. treatment, The use alkaline liquors, may be reduced of too strong a chemical solution for'toolong atime, is to be avoided, since too extended a treatment will out down the absorptivity ofthe a A v I -.W hen cotton hull fiber, namely minute seed hairs obtained from cotton seed hulls after the removal of the cotton and cotton linters, containing a substantial proportion of hull particles, is cooked by the calcium or sodium pentasulphide. process, substantiallyas described previously for jute or flax tow, thehull a heater or. other fiber 'disin engine and form a very good absorptive those to be fibers may be prepared tegrat s fiber.

Of these three classes of fibers, used principally for filler as follows: Cereal or other crop fibers, such as wheat straw, rye straw, barley straw. and others when thoroughly cooked by the calcium or sodium pentasulphide process and washed to free the cooked fiber from spent defibering engine. These same raw materials may also be cooked at other alkali of wards washed and beaten, or they may be cooked and beaten in abeating engine at-90-l'00 C. in the presence of a 10% solution of caustic i. e. a solution containing caustic soda in amount equal to 10% of the weight of the straw. When so treated such fibers are low in strength andsaturating capacity and, therefore, may be used asv filler fibers. 1

Thus I have described various processes for producing each of the three types of fibers, .any number of which I may einplo n Depending upon the t of felt desired to be produced, ,and the matte incorporated therein, various. percentages of each or various percentages of only two of the three may be employed. For instance,

rs may; also be produced by particles become sof- .tened to such an extent that they yield readily to the action of oat straw, rice straw,

in a beating or an elevated temperature and pressure in sodium carbonate, caustic soda or moderate percentage and after.-

11' a sheet of high strength is desired and high absorptive capacity is not necessary, strength and. filler fibers alone may be combined. "If a sheet of high absorptive and absorptive fibers alone may be combined. Ii"an average sheet is desired all three ypes of fibers -may be combin the fillerfiber being added, because usually of low cost, to bring up the weight of the sheet. Y

For some kinds of-building paper-I find it quitesatisfactory to'use a felt furnish of approximately 15% cooked jute fiber or cooked fiax tow or other cooked strength fiber and 85% well cooked. cereal crop fiber which, altho moderately non-absorptive, nevertheless, has sufiicient ab- A sheet thus produced may have a saturating.

as200% basedupon thedm,

capacity of as high I weight of the felt being saturated. Any one or more ofthe above may be used in the same felt f or one or more of them may be used in g nnection' with the old type 01 rag furnish as substitute for all or part ofany one class of raw prepared rags ,or-fibera,

- In other words, my'invention contemplates the matter of accurate control during the production of the felt. If a sheet of great strength is desired a greater percentage of strength fiber should beadded. Ifa sheet of high absorptive capacity is desired a greater percentage of the class of absorptive fibers should be added to the furnish. The'quality of the finished product is bound ,to vary from time to timebecause of 11'! regularity'of raw materials; and it is contem- "plated by this invention to regulate the finished product by slightly increasing or decreasing the constituentsof the furnish, such as adding or subtracting from the percentage of filler fibers used, or increasing or decreasing the amount of absorptive fibers employed. r

Among the advantages of my invention are that inexepensive 'raw materialsare employed, which materially v not, the conversion of these raw materials into fibers of the proper quality is readily accomplished, a felt of any desired quality may easily be obtained and the uniformity .of any particular type of felt :can be easily maintained during its manufacture.

lclaimzv 4 1. The process of producing roofing felt which comprises cooking jute fibers to produce fibers which when incorporated in the felt impart strength thereto, separately cooking vegetable fibers to.

cooking cereal fibers under conditions of increased severity as comparedwith the treatment of the said vegetable fibers, and admixing the three types of fibers thus produced in the proportion of from approximately 15 to approximately per cent'of strength fibers, approxisorptive fibers, and the remainder cooked cere fibers-to produce I strength and absorptive characteristics.

2. The methodof producing roofing felt which capacity is desired, strength.

sorptive capacity to give, together with the sulphite or kraft pulp, approxi-:.

felt' produce absorptive fibers, separately reduces the cost of the finished prod- 'mately 40-to approximately 8.5 per cent of a. felt sheet having the .desired fibers to produce filler fibers,

comprises beating jute fibers in an alkaline solution to produce fibers which when incorporated in the felt impart strength thereto, beating straw fibers to produce absorptive fibers, beating cereal fibers under conditions of increased severity as compared with the treatment of the said straw 4 and blending 'the three types of fibers in desired proportions to produce a felt sheet having the desired strength and absorptive characteristics. 1

3. The process of producing felt which comfelt,

prises cooking jute fibers to produce fibers imparting strength to the sheet in which they are incorporated, beating vegetable fibers to produce fibers imparting high absorptive characteristics to the sheet inwhich they are incorporated, beating cereal fibers under conditions of increased severity as compared with the treatment of the said vegetable fibers to produce filler fibers, and blending the three types of fibers in desired proportions to produce a felt sheet having the desired strength and absorptive characteristics.

prises beating jute fibers to produce fibers imparting strength to the sheet in which they are incorporated, cooking vegetable fibers to produce fibers imparting high absorptive characteristics to the sheet in which they are incorporated, cooking cereal fibers under conditions of increased severity as compared with thetreatment of the.

said vegetable fibers to produce filler fibers, and blending the three types of fibers in desired proportions to produce a felt sheet having the desired strength and absorptive characteristics. 6. The process of producing felt which comprises treating jute fibers in an alkaline solution to ,produce fibers which when incorporated in the felt impart strength thereto, treating straw in water at an elevated temperature to produce absorptive fibers, and blending the resultant fibers to produce a felt sheet having the desired strength and absorptive characteristics.

7. A roofing felt comprising jute fibers beaten in an alkaline solution, said fibers-imparting strength to said felt, straw fibers beaten *to produce absorptive fibers, and filler fibers formed by beating cereal fibers under conditions of increased severity as compared with the treatment of said straw fibers, said three types of fibers.

being blended to produce a felt having the desired strength and absorptive characteristics.-

8. A roofingfelt comprising jute fibers beaten to produce fibers imparting strength to' said felt, vegetable fibers cooked to produce fibers imparting high absorptive characteristics tosaid felt and cereal fibers beaten under conditions of increased severity as compared with treatment of said vegetable fibers to produce filler fibers, said threetypes of fibers being blended in dc sired proportions to desired strength and absorptive characteristics.

9. A roofing felt containing jute fibers which have b'eentreated in analkaline solution to proproduce a sheet having the duce fibers which impart strength to said felt, absorptive fibers produced by treating straw in water at an elevated temperature, said fibers being blended to produce a felt sheet having the desired strength and absorptive characteristics.

10. As an article of manufacture, a roofing felt consisting of jute fibers imparting strength to the felt, straw fibers having the characteristics of incompletely disintegrating straw which imparts high absorptive characteristics to the and cereal fibers having the characteristics of cereal straw more completely disintegrated than theaforementioned straw fibers.

11. As an article of manufacture, felt consisting of from approximately 15 to approximately 25 per cent jute fibers, approximately 40 to approximately 85, per cent straw fibers having the characteristics of incompletely disintegrated straw which impart high absorptive characteris tics to the felt, and the remainder cereal fibers having the characteristics of cereal straw more completely disintegrated than the aforemenfelt sheet having the dey tioned straw fibers. I

12. The process of producing felt paper which comprises blending jute fibers which have been cooked by the pentasulfideprocess with felt paper making material that will give high saturating qualities to a sheet and forming a sheet of felt paper containing said components.

13. The process of producing felt paper which comprises making a pulp containing jute cooked by the pentasulphide process and substantially resolved into its sessing only a moderately absorptive quality for waterproofing saturants and forming a sheet from said pulp.

14. As an article of manufacture, a felt paper" consisting of vegetable fibers cooked in such a manner that their original strength remains sub- :stantially unchanged, material that imparts high saturating qualities to the paper and a filler fiber of only. moderately absorptive quality made by alkaline polysulfide solution. of manufacture a felt paper cooking straw in an 15. As an article consisting of 15% to 25% of jute which has been cooked by the pentasulfide process, 40% to of crop fibre which has been cooked partially to such an extent as to give high saturating qualities to the sheet and 35% or less of vegetable crop fibre which has been thoroughly cooked to impart high strength quality thereto, substantially as described. V

16. Asan article of manufacture, a felt paper consisting of 25% cooked jute, 40% cooked absorbent fiber from a straw, and 25% well cooked filler fiber from a straw.

1'1. A process for the production of a felt paper which comprises cooking jute in an alkaline medium, cooking a straw in the presence of water for a period of time sufilcient only tothoroughly soak the straw, thoroughly cooking a straw in an alkaline medium until a fiber possessing little strength is obtained, and then blending the resultant fibers, pulping the blended mixture offibers, and sheeting the pulped mass.

' the blended mixture of fibers, and sheeting the v 18. A process for the production ofa felt paper which comprises cooking jute in an alkaline medium at a temperature of from about to and then blending the resultant fibers, pulpin pulped mass. I

about 90 to ion" c., thor-' ultimate fibers, said fibers pos-.

' in the manufacture of felt base verted into strength fibers claim 22 in which the ence of a polysulfide to -(a) cooked 'jute being produced by fibers as such the treatment of the wood absorptive fibers, said saturated fel't' sheet coniii. A process for the production of a felt paper which comprises cooking a straw in the presform a strength fiber, an

absorptive fiber, and afiller fiber, blending the 20. A bitumen-saturated felt adapted for use roofing, comprising strength, absorptive, and filler fibers, the

strength fibers being selected from the group:

(a) cooked jute fibers, (b) beaten jute fibers,

and (0) wood fibers converted into strength fibers by chemical treatment under conditions ofin-' creasedseverity as compared with the treatment of the wood fibers converted into absorptive e group: (1) wood fibers converted into absorptive fibers. by chemical treatment and (2) annual vegetable crop fibers, and .the filler fibers being constituted of annual vegetable crop fibers treated under conditionsof increased severity as comcrop fibers constituting the absorptive fibers;

strength fibers being selected from the group: bers,"(b). beaten jute fibers, and (0) wood fibers converted into strength fibers by chemical treatment under conditions of increased. severity as compared with the treatment of thewood fibers converted into absorptive fibers, theabsorptive fibers being selected from the groupr (1) wood fibers converted into absorptive fibers by chemical. treatment and (2) annual vegeta e crop fibers.- 22. Bitumen-saturated felt adapted for use in the manufacture of felt base roofing comprlsina strength and absorptive fibers, both of said fibers: chemical treatment of wood I and as distinguished from the treatment of paper or rags; the wood fibers'conbeing treated under conditions ofincreased severity as compared with taining bituminous saturant loan amount equal to at least 200 percent of' the weight of the felt. I -23. A bitumen-saturated 'felt as defined in strength fibers are selected u from the group: sulphite pulp and Kraft pulp.

. 22in which-the 5.5

24, A bitumen-saturated felt as defined in being selected from of the annual vegetable f fibers converted into a,oao,s1o'

26. Bitumen-saturated felt adapted for use inthe manufacture of felt base roofing comprising strength and absorptive fibers,'-th e strength fibers being produced by pulping of wood fibers as such'andas distinguished from the treatment of paper or rags and the absorptive fibers being produced by the mechanical disintegration of 1 annual crop fibers in an aqueous medium, said saturated felt sheet containing bituminous saturant in an amount equalto at least 200 per cent of the dry weight of the felt.

27. A felt sheet adapted to be'saturated with waterproofing mate and comprising strength fibers from the group:

pulp, and absorptive fibers prepai'ed by disintegrating fibers of vegetable origin in an aqueous;

sulphite pulp-and kraft medium so asto increase their absorptive capac- -ity, the absorptive fibers being blended with the strength fibers after disintegration of the absorptive fibers and before sheeting the resultant -mixture' weight of the unsaturated 2s. A felt sheet adapted to be saturated with.

2a A felt sheet adapted to be saturated with.

bituminous ma u U of felt -base roofing consisting entirely of wood fibers and annual crop fibers. 4

30. A process for producing felt which comprises treating wood with a solution of caustic soda, the amount of caustic soda employed being at least 10 per cent of the temperatures of not lessthan 90 C. to produce fibers of high absorptive capacity, mixingsaid fibers with other fibers and forming themixture into a felt sheet. of high absorptive capacity. 1

.31. A process as claimed in claim 30 in which the said otherfibers are of greater strength but less absorpti e wood fibers.

a2. a process or produclng'felt which comprises treating wood witha solution of caustic soda at a temperature of not lessth'anl 90 C. .to produce fibers of open {structure absorptivity. mixing said u and forming e resultant mixture of fibers into af'elt sheetp' V 33. A waterproof felt sheet comprising a sub stantial proportion of wood-fibers of high- 8b? sorptive stances with a peratures higher than said felt being satin-ant.

solutionof caustic alkali-at temweight of the wood, at,

capacity 'thansaid absorptive and-high fibers with other fibers 90 0.; and other fibers.

with a tcrial forum in the manufacture capacity produced by treating wood sub'--- I 'CERTIFICATE or CORRECTION.

Patent No. 2,029,610. February 4, 1936.

' PIERRE maswssn.

ereby certified that error appears in the printed specification of t requiring correction as follows: Page 5, second column, line 9, claim 10, for "disintegrating" read disintegrated; line 55, claim 16, for "25%" read 55%; and that the said Letters Patent should be read with these corrections therein that the same may con of the case in the Patent Office.

Signed and sealed this 3rd day of March, A. "D. 1936.

It is h the above numbered paten Leslie Frazer (Seal) Acting Commissioner of Patents;

form to the record 

